Spliced object not aligning

[jpm021990 0]

Hi guys,

I have a Ultimaker 2 and I'm trying to print a couple of spliced designs that were cut down the middle for easier printing. The problem I'm having is that after both sides print out the object does not align with the other half. It happens with pretty much every design. I would be okay with a minor overlap but this is about a 1/4" around most of the print.

If I align the top perfectly then the bottom does not match. I'm not sure why this is happening as other people have used the same design without any issues.

Any thoughts/comments?

Printing with Colorfabb Black PLA 215c 45mm/s print speed .2 layer height

(Picture is the night night gun from Agents of Shield)[/media][/media]

[jpm021990 0]

[jpm021990 0]

[yellowshark 153]

I am printing ColorFabb Dutch orange at 50mm/s, .300 layer and 205c extruder. I would say your 215c is too hot and that maybe that is affecting your dimensions. Somewhat of a guess but 1/4inch out is a LOT.

[IRobertI 521]

1/4in is ~6mm to save some time for those of us who don't count with our fingers and toes

And yellowshark is right, that's a very large error in dimensions. Are you sure the two halves line up digitally as well? Have you tried printing a circle, is it an actual circle? Have you tried printing a square, is it an actual square?

Also, you're underextruding quite heavily. Try doing a few Atomics and/or replace your PTFE coupler if you've been printing for a long time.

And it looks like you don't have enough top/bottom thickness to close the top properly. It could also just be because of the underextrusion.

[jpm021990 0]

1/4in is ~6mm to save some time for those of us who don't count with our fingers and toes

And yellowshark is right, that's a very large error in dimensions. Are you sure the two halves line up digitally as well? Have you tried printing a circle, is it an actual circle? Have you tried printing a square, is it an actual square?

Also, you're underextruding quite heavily. Try doing a few Atomics and/or replace your PTFE coupler if you've been printing for a long time.

And it looks like you don't have enough top/bottom thickness to close the top properly. It could also just be because of the underextrusion.

 

My circles and squares come out perfectly. I've tried with 2 different designs for the gun and they still have the same result

I realized i did the wrong settings for the first picture why it looks so bad, the other side looks a lot better because i changed the settings.

My PTFE coupler is new and I do regular atomics.

https://www.thingiverse.com/thing:1460236/#files

[jpm021990 0]

I am printing ColorFabb Dutch orange at 50mm/s, .300 layer and 205c extruder. I would say your 215c is too hot and that maybe that is affecting your dimensions. Somewhat of a guess but 1/4inch out is a LOT.

 

I'll try with 205 but I don't think it would make too much of a difference. My only issue with the printer is when lining up spliced pieces

[yellowshark 153]

Beware that if you do have some under-extrusion, dropping the temp will not help you; equally raising the temp to overcome under extrusion is not the right solution! No it may not help, just a guess as the temp is obviously wrong. If you are printing the same piece, albeit rotated 180 degrees, such a dimensional error is difficult to understand, especially if every thing else is coming out fine. Does it just look fine or is it dimensionally accurate to within 100 microns?

[yellowshark 153]

Wondering why you are doing regular atomics? I am sure everyone is different but I did my first one for about year yesterday and only because I was changing from orange to black and being lazy. To me if you are doing them regularly then you are either switching between different types of filament regularly (I do not) or you have an issue somewhere.

I just say that because it is difficult to work out what is going on.

Edited April 23, 2016 by Guest

[jpm021990 0]

Wondering why you are doing regular atomics? I am sure everyone is different but I did my first one for about year yesterday and only because I was changing from orange to black and being lazy. To me if you are doing them regularly then you are either switching between different types of filament regularly (I do not) or you have an issue somewhere.

I just say that because it is difficult to work out what is going on.

 

I do them regularly because I switch from ABS/PLA often, its more of a precaution. The prints themselves look absolutely fine. You can totally ignore the first picture. I printed with faster settings and less infill. I'm really at a loss for this too because I've tried with the full design and splicing it myself and using the already spliced one with the same result.

Here's a totally different design where the same thing happened. On the top its totally fine and then the bottom half just wont align. Or if I align the bottom the top doesn't line up

[yellowshark 153]

PLA/ABS, OK :)I was thinking about your problem. If your printer IS dimensionally accurate - refer my last comment in previous post then my view is that it is impossible to be out by 1/4" / 6mm. Maybe a few hundred microns but not 6000 microns. 1st three pics are of two pieces I printed yesterday, laying one on top of the other - 17cm just under 7 inches wide. The fourth pic demonstrates a 1/4" 6mm error.

[media=14871][/media]

[media=14872][/media]

[media=14873][/media]

[media=14874][/media]

In my view that is IMPOSSIBLE. Either you have something physically wrong with your printer and it is dimensionally inaccurate, or, something is wrong with the two models and they are not dimensionally the same. Or whatever slicer you use is cr*p - I use Cura.

With 45mm/s you should be getting within 100 microns.

Just love Agents of Shield btw

Edited April 23, 2016 by Guest

[jpm021990 0]

PLA/ABS, OK :)I was thinking about your problem. If your printer IS dimensionally accurate - refer my last comment in previous post then my view is that it is impossible to be out by 1/4" / 6mm. Maybe a few hundred microns but not 6000 microns. 1st three pics are of two pieces I printed yesterday, laying one on top of the other - 17cm just under 7 inches wide. The fourth pic demonstrates a 1/4" 6mm error.

[media=14871][/media]

[media=14872][/media]

[media=14873][/media]

[media=14874][/media]

In my view that is IMPOSSIBLE. Either you have something physically wrong with your printer and it is dimensionally inaccurate, or, something is wrong with the two models and they are not dimensionally the same. Or whatever slicer you use is cr*p - I use Cura.

With 45mm/s you should be getting within 100 microns.

Just love Agents of Shield btw

 

I use Cura as well. I'm trying to take one of the halves and mirroring it using Cura now instead of printing the models separately. I'll let you know how it goes. Its so weird because most of it lines up but the whole thing will not

[yellowshark 153]

Have you checked the dimensions of the two models in Cura? It would not necessarily pick up the difference, but it might.

[yellowshark 153]

Robert commented that you had under extrusion and he may well be right but I am wondering if that poor surface is due to pillowing. Did you swap from ABS to PLA and forget to set your fans on? What % infill are you using and what layer height and bottom/top thickness do you have?

[jpm021990 0]

Robert commented that you had under extrusion and he may well be right but I am wondering if that poor surface is due to pillowing. Did you swap from ABS to PLA and forget to set your fans on? What % infill are you using and what layer height and bottom/top thickness do you have?

 

Nope I set the correct filament type. 20% infill, .8 bottom top thickness, 1.2 shell .2 layer and 45mm/s print speed

I fixed the issue where there was a little pillowing, that picture was a bad one to choose, I have another half that I printed that looks physically perfect but still the same amount of offset when you try to put them together

[IRobertI 521]

Extreme longshot: Which version of cura are you using? Are you using the "next generation" with the new interface? If so, maybe autoscaling could be the culprit? It seems extremely unlikely since the print doesn't look all that big and I would think cura would scale both pieces equally to make them fit if that was needed.

[jpm021990 0]

Extreme longshot: Which version of cura are you using? Are you using the "next generation" with the new interface? If so, maybe autoscaling could be the culprit? It seems extremely unlikely since the print doesn't look all that big and I would think cura would scale both pieces equally to make them fit if that was needed.

 

Cura 15.04.4

I actually had to scale them both to .8 of what they originally were to make it fit on the build plate

[yellowshark 153]

OK. Just as a hint, personally I think .8 /4 layers for bottom/top thickness with 20% infill is a bit marginal. Strange one this; I would urge you to print something else of known dimensions and measure it. You do not seem to be doing anything substantially wrong but the printer would just not normally have that enormous margin of error. Do you want to post the two models somewhere so I can have a look and maybe print them?

[jpm021990 0]

OK. Just as a hint, personally I think .8 /4 layers for bottom/top thickness with 20% infill is a bit marginal. Strange one this; I would urge you to print something else of known dimensions and measure it. You do not seem to be doing anything substantially wrong but the printer would just not normally have that enormous margin of error. Do you want to post the two models somewhere so I can have a look and maybe print them?

 

The other half just finished printing and its exactly the same as the previous one. I'm really at a loss for this. What do you recommend for bottom top thickness and infill?

Here are the 2 different ones I tried, the first one I cut it myself using netfabb, the 2nd one was already pre-cut, but the same thing happens for both

http://www.thingiverse.com/thing:387245/#files

https://www.thingiverse.com/thing:1460236/#files

[yellowshark 153]

Thanks for the files, if I don’t look at them today, definitely tomorrow.

To my mind there is no one simple answer as it does depend on the combination of layer height and infill %.I do not think of it in thickness, I think of it in terms of number of layers, which then of course has to be converted to a distance. I often use 40% infill, which in relative terms is quite solid. With 0.3 layer height I will use 3 layers . If I were using 0.1 layer height I would put down 4 or 5 layers. With 20% infill and 0.3 layer height I would use 4 layers; with 0.1 layer height I would put down about 10 layers minimum.

The problem with sparse infill is that your first top layer will fail and even more so with a thinner layer height. The next layer will recover the position to some extent but probably not 100% even with 0.3 layers and you may still have a mess which will still need at least one layer but probably two to get rid of and give you a smooth finish. With thinner layer heights you get a greater mess on the first pass because the thinner layer just does not cover the gaps as well as a thicker layer and you need a lot more layers to get the get the job done. Obviously if printing something with a large base, say 10*10 inches, then it makes sense to try and get away with the minimum as each layer can take a considerable time to print.

If you have a large model and are not sure, then you can test it by using the Cura parameter “cut off object bottom” on the Advanced tab; you can set the distance appropriately so that you just print the upper layers. It is a long time since I have done it but I think if you also un-tick “sold infill bottom” on the Expert settings you will get the first layers you print as infill, so the whole thing does not need to take very long to print.

[jpm021990 0]

Thanks for the files, if I don’t look at them today, definitely tomorrow.

To my mind there is no one simple answer as it does depend on the combination of layer height and infill %.I do not think of it in thickness, I think of it in terms of number of layers, which then of course has to be converted to a distance. I often use 40% infill, which in relative terms is quite solid. With 0.3 layer height I will use 3 layers . If I were using 0.1 layer height I would put down 4 or 5 layers. With 20% infill and 0.3 layer height  I would use 4 layers; with 0.1 layer height  I would put down about 10 layers minimum.

The problem with sparse infill is that your first top layer will fail and even more so with a thinner layer height. The next layer will recover the position to some extent but probably  not 100% even with 0.3 layers and you may  still have a mess which will still need at least  one layer but probably two to get rid of and give you a smooth finish. With thinner layer heights you get a greater mess on the first pass because the thinner layer just does not cover the gaps as well as a thicker layer and you need a lot more layers to get the get the job done. Obviously if printing something with a large base, say 10*10 inches, then it makes sense to try and get away with the minimum as each layer can take a considerable time to print.

If you have a large model and are not sure, then you can test it by using the Cura parameter “cut off object bottom” on the Advanced  tab; you can set the distance appropriately so that you just print the upper layers. It is a long time since I have done it but I think if you also un-tick “sold infill bottom” on the Expert settings you will get the first layers you print as infill, so the whole thing does not need to take very long to print.

 

Ok I just changed some of those settings and printed it but still with the same result (I also scaled it using a different method than Cura as per another suggestion) but it came out exactly the same. I'm looking forward to what you uncover in your test print.

[gr5 2,224]

6mm is crazy off.

Is it possible one or both of the parts are warping off the glass bed? If you don't do everything properly the part will pull itself off the glass at some point. Once that happens all bets are off.

Other than that guess, I really doubt the problem is with the printer - I mean does the printer sit flat on the table? Or does it rock? Does it look like a parallelogram when viewed from above?

More likely something went wrong with the scaling step or the split step or the model is bad.

I'd check if the 2 halves line up *before* printing. Maybe check the gcodes and measure by counting the 10mm squares on the print bed in cura. You should be able to see the error there.

[jpm021990 0]

6mm is crazy off.

Is it possible one or both of the parts are warping off the glass bed?  If you don't do everything properly the part will pull itself off the glass at some point.  Once that happens all bets are off.

Other than that guess, I really doubt the problem is with the printer - I mean does the printer sit flat on the table?  Or does it rock?  Does it look like a parallelogram when viewed from above?

More likely something went wrong with the scaling step or the split step or the model is bad.

I'd check if the 2 halves line up *before*  printing.  Maybe check the gcodes and measure by counting the 10mm squares on the print bed in cura.  You should be able to see the error there.

 

WOW

You're totally right, one of the bars across the top is actually at an angle, about 6mm too. How can I fix that?

[gr5 2,224]

Is it too late to return the printer?

You don't need it perfectly square but... If you can see the error by eye then it needs to be fixed.

You could try loosening but not removing all the screws that hold the 4 sides and the top together and then push the printer into the correct shape and retitghten. Basically you need to undo the damage done by shipping (this is always shippings fault - I think they hire elephants). So you could try to have an elephant sit on the printer in the other direction to push it back to square (or try my loosening the screws method).

[gr5 2,224]

Also when you go to print the second half of you model, flip it about the X axis (or Y axis) first so it is flipped upside down - then rotate it 90 degrees about the Z axis so that if it is squished slightly into a parallelogram it will match the parallelogram of the other half.

To visualize this it might help to kind of draw a parallelogram with equal length sides and flip it and then rotate it about Z by 90.

Edited April 27, 2016 by Guest